Double toggle-lever press



Sept. 14, 1965 R. NEUBAUER ETAL 3,205,551

DOUBLE TOGGLE-LEVER PRESS Filed April 1o, 196s 2 sheets-sheet 1 Sept. 14, 1965 R. NEUBAUER ETAL 3,205,551

DOUBLE TOGGLE-LEVER PRESS Filed April lO, 1963 2 Sheets-Sheet 2 INVENTORS United States Patent This invention relates to a double toggle-lever press for moulding loose material and particularly for making concrete blocks, such presses having rams adapted to be moved in opposite directions.

In the moulding of blocks from loose material, as uniform a density as possible is desirable over the entire cross-section of the block. This requirement cannot be fully achieved, because of the presence of the so-called `pressure cone which does not permit even compacting of the material, and on that side which is remote from the pressure ram the material is less dense. If compression of the material is carried out from both sides with pressures of equal value and with the same length of travel, a zone of lower density, the so-called neutral zone, is formed in the middle of the block. Depending -on the construction of the press, it is possible, by suitable regulation of the pressure applied, to move the neutral zone as desired away from the middle of the block. Such presses are costly, in particular in the case of hydraulically-operated presses, first because the drive has to be duplicated, and second because the drive requires special control arrangements. For that reason, use is generally made of compression from one side only and a so-called lloating mould. In that construction, the press mould is resiliently suspended and, when a certain applied moulding pressure is reached, the block of material is displaced in the mould and the friction of the material against the wall of the latter is reduced. It is true that a certain improvement can be achieved by that measure, but it is not possible to obtain a well-dened position of the neutral Zone.

The invention provides a double toggle-lever press having rams adapted to be moved in opposite directions and which, in spite of its comparatively simple structure, makes it possible to produce from loose material stone slabs having a substantially uniform density over their entire cross-section.

According to the invention the toggle-levers are connected to an upper ram and to the drive therefor, for example the piston rod of a hydraulic cylinder, and, the levers, are also supported on `columns rigidly connected .to a lower ram, further, the end position of the upper ram is so dened by a stop that after that end position has been reached the lower ram is raised.

In that way, the advantageous effect is obtained that the upper ram exerts only an initial compression up to a predetermined pressure, after which the further compression is then eitected by the lower ram, whereby the neutral zone is eiectively transferred to the midlevel of 'the block or the zone can be brought to another desired position.

By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompanying drawing which shows the embodiment 4in schematic elevation, of which FIG. 1 shows the upper ram is raised position and FIG. 2 shows the upper ram .in rlower position.

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gle-lever systems 12, 13. The upper arms 12 of the toggle-lever system are connected in each case by way of bearing pins 14 to the columns 2 while the lower arms 13 engage the slide 5 by way of joint pins 15. Above the lower ram 4 is a press table 16 with a mould 17, the lower opening of which is closed by the lower ram 4. The position of the rams shown in the drawing is the upper poistion of the toggle-levers in which the slide 5 and the upper ram are in the highest position indicated by chain dotted line 1.

The mould 17 is iirst lled with an accurately weighed quantity of material, and the hydraulic cylinder 7 is energized to move the slide 5 with the ram 6 mounted therein towards the material to be moulded. Theram 6 enters the mould 17 and compacts the material to an eX- tent determined by a pre-set applied pressure. That position is indicated by chain dotted line II. This depth of penetration of ram 6 into the mould is limited by vertically adjustable stops 18 arranged on the press frame. As the slide 5 strikes against those stops, the bearings 15 which are mounted on the slide now lbecome the point of `support of the toggle-lever systems, and the joint pin 15 mounted on the slide 5 now forms the abutment for the toggle system, whereby the arms 12 raising the columns 2 by way of the bearing pins 14 and thereby pressing the lower ram 4 into the mould. In this process, the lower ram is brought from the position indicated by chain dotted line III into the upper position indicated by chain dotted line IV.

The compression process of the invention is distinguished from that of known presses because in the latter an abutment for the initiation of the movement of the counter or lower ram is formed by the material itself. In the process of the present invention, that position of the press lram in which the pressure in the material has risen `so high that the moulding material itself becomes the point :of reaction and support and thereby causes the reversal of the direction of compression is not reached. Although a far longer compression path could be covered by the upper ram 6, and the lower ram 4 could come into use at a very late point and have a very short travel, such a process would result in the neutral zone being undefined and not positioned in the middle of the block. Because the slide 5 strikes the stops 18, the movement of and pressure applied by ram 6 is restricted and a suiciently large range of travel and pressure is left for the lower ram 4. Thus, by suitable adjustment of stops 18, accurate displacement of the neutral zone is possible.

In the drawing, the force exerted by the lower ram 4 is in the range of the maximum force developed by the toggle-levers, so that the compression work is obtained along a path of movement shorter than that of the upper ram. Thus, the block, already precompressed vby the upper ram, is once more compressed by the lower ram with a considerably greater pressure. This final pressure can be regulated by an adjusting screw 19 on slide 5 and with which the descending piston rod comes into contact via a supporting plate 20 on the crosshead 9. This arrangement serves as a safetyfdevice against possible destruction of, or damage to, the press which may occur in view of the forces produced in the extended position. The lower ram is also adjustable in position. A pair of tapered discs 21, the lower one of which is rotatable and is provided with a Vernier, permits very accurate adjustment.

Moreover, as will be seen from the drawing, the lower ram 4 is mounted on the piston rod of another hydraulic 3 cylinder 22 which is detachable. the material has been completed and the pressure on the upper ram 6 has been released,vpressure medium is admitted into the hydraulic cylinder 22 and the moulded material is lifted out of the mould by upward movement of ram 4.

We claim: 1. A toggle-lever press for moulding material com- After the moulding ofV prising in combination a mould for holding material to be moulded, rst and second rams movable towards and away from said mould, support columns secured to said second ram, a mechanism for moving said rst ram towards and away from said mould, toggle-levers connected between said mechanism, said rst ram and said support vcolumns and stop means for limiting the movement of said first ram towards said mould, said toggle levers comprising the sole drive for the reciprocal pressure movement of both rams.

` 2. A toggle-lever press yfor moulding material asclaimed in claim 1 and further comprising slide means movable on said support columns and mounting means on said slide means for said rst ram.

3. A toggle-lever press for moulding materialcomprising a framework, a mould for holding material to be moulded, mounting means on said framework for said mould, support columns mounted in said framework and longitudinally movable with respect thereto, rst and secondv rams movable towards and away. from said vmould, mounting means on said second ram for receiv ing said support columns,`avmechanism on said framework for moving said rst ram towards and away from said mould, toggle-levers connected between said mechanism, said rst ram and said support columns for transmitting movement to `said second ram and stop means lon said framework for limiting the movement of Vsaid rst ram towards said mould, said-toggle levers comprising the sole drive for the reciprocal pressure movement of both rams.

4. A toggle-lever press for moulding material comprising in combination a mould for holding material to be moulded, first and second rams movable towards and away from said mould, support columns, a slide member secured to said support columns, an adjustable mounting device on said slide device for receiving said second ram,

ya mechanism for moving said first ram towards and away from said mould, toggle-levers connected between Asaid mechanism, said rst ram and said support columns for transmitting movement to said second ram, and stop means for limiting the movement of said first ram towards said mould, said toggle levers comprising the sole drive for the reciprocal pressure movement of both rams.

5. A toggle-lever press for moulding material comprising in combination a mould for holding material to be moulded, rst and second rams movable towards and 4away from said vmould, support columns, a slide member secured to said support columns, mounting means 'on said slide member for said second ram, a mechanism `for moving'said second ram relatively to said slide member, a'further mechanism for moving said tirst ram to- 'wards and away from said mould, toggle-levers connected between said further mechanism, said rstram and'said support columns for imparting movement to said second ram, and stop means for limiting movement of said rst `ram towards said mould, said toggle jlevers Vcomprising the sole drive for the reciprocal pressure movement of both rams.

6. `A toggle-lever press for moulding material comprising in combination a mould for holding `material to be moulded,.irst and second rams movable towards and -away frornsaid mould, support columns, a slide mem- Aber secured to said columns, mounting means on said slide rmember for said second ram, a hydraulically-operated piston-cylinder mechanism carried by said slide .member vfor moving said secondram relatively to said Vsaid rst ram towards said mould, said toggle* levers comprising the sole drive for the reciprocal pressure movement of both rams.

7. A toggle-lever press for moulding `material comprising in combination a mould for holding material to be moulded, first and second rams movable towards and away from said mould, support columns secured to said second ram, a' mechanism for moving said rst ram towards and away lfrom said mould, toggle-leversinterconnected between said mechanism and said 'support columns for imparting movement to said second ram, adjustable stop means associated with said first ram for controlling pressure applied by said toggle-levers to said second ram, and stop means for limiting the movement of said rst ram towardsusaid mould, said toggle levers comprising the sole drive for the reciprocal pressure movement of both rams.

k8. A toggle-lever press for moulding material comprising in combination, a mould for holding material to be moulded, rst and second rams movable towards and away from said mould, support columns secured to said second ram, a mechanism for moving said first ram towards and away from said mould, toggle-levers interconnected between said mechanism and said support columns for imparting movement to said second ram, and adjustable stop means for limiting movement of said first ram towards said mould, said toggle levers comprising the sole drive for the reciprocal pressure movement` of both rams. I

9. A press for moulding materials comprising a press frame, a hydraulic cylinder and piston rod mounted on an upper part of-the frame, and the piston rod connected to a cross head, a pair of columns suspended in the frame, a slide guided on the columns and having an upper ram mounted thereon, a mould mounted in the frame having upperand lower openings, a lower ram mounted on the columns and cooperating with the lower opening of the mould to close ythat end thereof, toggle levers pivotally connected to the cross head and the slide, an upper arm connected at one end on the column and the other end to the toggle levers so that when the piston rod is actuated the cross head will force the slide downwardly and the lower ram upwardly simultaneously with lthe upper ram ybeing forced into the mould to compress the material in the mould bythe combined action of the vupper and lower rams.

10. A press according to claim 9, in which a cross piece isV provided mounted on the columns and on which the lower ram is secured. n y

11. A press according to claim 9, in which a plurality of stops are secured on the frame acting as abutments for the slide'.

12. A pressV according to claim 9, in which the toggle levers comprise two levers pivotally connected to each other with the upper arm connected to the pivotal connection of both levers of the toggle levers.`

13. A press according to claim 9, in which a supporting plate and an adjusting screw are provided with the plate mounted on the cross head and the screw mounted`on the slide to act as a safety device for the press when the latter is in an extended position.

14. kA press according to claim-9, in which a cross piece is provided mounted on the columns and on which the lower ram is secured, and in which means are provided connected to the lower ram and the cross piece to permit adjustment for the lower ram.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS 1/90 Tubbs 25-41 8/07 Webb 100-272 5 13 Hill 10C-264 6/18 Whitney 25-91 2,342,772 2/44 Wellman 25--84 2,556,951 6/51 Weidner 25-90 CHARLES W. LANHAM, Primary Examiner.N

5 ROBERT F. WHITE, WILLIAM J. STEPHENSON,

Examiners. 

1. A TOGGLE-LEVER PRESS FOR MOULDING MATERIAL COMPRISING IN COMBINATION A MOULD FOR HOLDING MATERIAL TO BE MOULDED, FIRST AND SECOND RAMS MOVABLE TOWARDS AND AWAY FROM SAID MOULD, SUPPORT COLUMNS SECURED TO SAID SECOND RAM, A MECHANISM FOR MOVING SAID FIRST RAM TOWARDS AND AWAY FROM SAID MOULD, TOGGLE-LEVERS CONNECTED BETWEEN SAID MECHANISM, SAID FIRST RAM AND SAID SUPPORT COLUMNS AND STOP MEANS FOR LIMITING THE MOVEMENT OF SAID FIRST RAM TOWARDS SAID MOULD, SAID TOGGLE LEVERS COMPRISING THE SOLE DRIVE FOR THE RECIPROCAL PRESSURE MOVEMENT OF BOTH RAMS. 